Problem: $\dfrac{1}{2} + \dfrac{2}{5} = {?}$
${\dfrac{1}{2}}$ ${\dfrac{2}{5}}$ $+$ ${\dfrac{1 \times 5}{2 \times 5}}$ ${\dfrac{2 \times 2}{5 \times 2}}$ $+$ ${\dfrac{5}{10}}$ ${\dfrac{4}{10}}$ $+$ $ = \dfrac{{5} + {4}}{10} $ $ = \dfrac{9}{10}$